This invention relates to an industrial robot used for welding, automatic assembling or the like.
Conventional types of robots of this kind can be roughly classified into two groups, that is, a first group including rectangular coordinate type units and a second group including joint type units. It has been usual to use a joint type unit in the case where installation space cannot be widely secured.
However, using the conventional joint type robot, in order to move a tool attached thereto linearly in the vertical direction and in the horizontal direction, while keeping a given posture thereof constant, it has been necessary that, as shown in FIG. 1, a turning table a has mounted thereon a first arm b which is tiltable in front and rear directions, a second arm c on an upper end of the first arm b which is tiltable in upper and lower directions, and a tool e attached to a forward end of the second arm c through a wrist mechanism d having a construction permitting movement in at least two axes. Thus a complicated robot results requiring the control of at least five (5) axes of movement in total.